Heat exchangers find application in chemical and process engineering for the transfer of heat between two media. The known plate type heat exchangers consist of a plurality of profiled sheets, which are assembled into a sheet pack. The wall thickness of the individual sheets, for strength reasons, is generally 0.4 to 0.8 mm. The sheet packs are mounted in a frame and clamped together with several tightening screws.
The heat-transferring media are guided through four plate openings at the corners of the sheets. Every two openings are alternately sealed off from the rest of the flow space so that the two media alternately flow through the intervals between the plates. By closing off individual passageways, it is possible to collect up all plates or certain plate packs in succession, in order to achieve a multiple path design (VDI Heat Atlas, 7thEd., 1994, Ob 18, 19).
There are familiar heat exchangers which work by the counterflow principle. Moreover, heat exchangers with a cross flow design are known.
Miniaturization of heat exchangers enables an enlargement of the outer surfaces available for heat exchange processes as compared to the total volume of the media flow. In this way, high capacities of heat transfer between the media are achieved.
A method for fabrication of fine structure bodies such as heat exchangers is known from DE 37 09 278 A1, in which grooves with constant cross section along their length are introduced into the surface of clarnpable metal foils and the foils are layered one on top of the other and joined together to form a microstructure body with channel-like passageways. In the known method, the grooves are worked into the foils with shaping diamonds. The method is not suitable for fabrication of microstructures with very large aspect ratios, i.e., the ratio between the height of the structure and its lateral dimensions, or structures with low surface roughness. Moreover, a free lateral structurizability is not provided, since the shaping diamonds can only form grooves with constant cross section along their length.
DE 39 15 920 A1 describes a micro heat exchanger with two layers of semiconductor material structured by etching. As a drawback, it turns out that metals are not accessible to this structurization.